Case studies

Extra high voltage network to be renovated in Hautes-Alpes

Breadcrumb

Context

We are involved in renovating the high voltage electricity network in Haute-Durance in south-eastern France. Led by public utility RTE, this large-scale project will mean that 200km of overhead power lines can be removed from the landscape by 2021.

200,000

hours worked

100

km of lines buried

112

transmission towers transported by helicopter

We put our expertise to work on this comprehensive electricity network upgrade programme in Haute-Durance. Two new overhead power lines were built on the mountainside so as to keep them away from homes.

The installation of two 225kV extra high voltage lines between Argentière and Serre Ponçon and between Grisolles and Pralong involved:

laying foundations for 160 towers

installing 584 blocks and 1,000 micropiles

pouring 35,000 cubic metres of concrete

unwinding 50km of line and 250km of cable

assembling 466 sections on platforms

Major environmental and local challenges

Since the works were being carried out in a mountainous area, a number of challenges had to be overcome, in terms of site access, weather and the environment. In order to minimise the impact of works on the environment, helicopters were used. For example, 112 towers were transported via helicopter. To preserve the landscape, towers that blended into the local environment were specially selected.

The project has strong local roots, with numerous jobs being created in the region to support it.

Overall, the project involved 250,000 hours of work and 140 people during peak periods. This large-scale programme strengthens our expertise in technically complex projects.